Correction to This Article
A graphic with the article about moves to change Senate rules on filibusters misstated the duration of a filibuster by William Proxmire (D- Wis.) on a 1981 bill to raise the debt ceiling. It lasted 16 hours, 12 minutes, not 6 hours, 12 minutes.

Back in 2005, McConnell had "majority" in his leadership title, and Republicans -- confident about their majority status -- pushed unsuccessfully to obliterate filibusters of judicial nominees. Now the shoe is on the other foot.

A growing number of Democrats, from senatorial veterans such as Vice President Biden to freshman Sen. Tom Udall (N.M.), are calling for a rules change that would transform the culture of long and sometimes tedious debate in the world's greatest deliberative body.

But these nascent efforts to curb the use of filibuster face resistance from Senate elders with long memories, who know that political winds can take today's large majority and create tomorrow's minority. Majority Leader Harry M. Reid (D-Nev.) has not scheduled any debate on the issue.

First in 1917 and then in 1975, the Senate formally set up rules for "cloture motions," the name given to the parliamentary device to shut down debate. It requires the affirmative votes of 60 sitting senators.

The Constitution cites only five requirements for Senate supermajorities, including impeachment convictions of presidents, but allows the House and Senate to set their own rules. Under long-standing resolutions, the Senate considers itself to be a "continuing body" whose parliamentary rules remain in effect unless a two-thirds supermajority votes to change them.

The more authoritarian House, whose entire membership stands for election every two years, sets its rules at the start of each Congress by a majority vote.

Last Thursday's swearing-in of Sen. Scott Brown (R-Mass.) ended the filibuster-proof majority that Democrats had held since July. This means all 59 members of the Democratic caucus would need the support of at least eight GOP senators to change filibuster rules, a tall order not likely to occur anytime soon. It also means that Republicans have the minimum number of votes, 41, needed to block President Obama's agenda.

Moments after administering the oath to Brown, Biden held court with reporters outside the Senate chamber, in which he had served for 36 years. He said he has tasked his staff to study the constitutional history of filibusters, to determine what steps could be taken.

"I've never seen a time when it's become, sort of, standard operating procedure," Biden said. "You want to get anything done, you have to have a supermajority. And I really mean this, unrelated to whether or not Barack and I are sitting down in the West Wing now. Any president in the future having to move through anything he or she wants, requiring a supermajority, it's not a good way to do business."

Sen. Tom Harkin (D-Iowa) has offered a resolution that would do away with filibusters in a four-step process, first requiring 60 votes and scaling down to a 51-vote majority for passage of any bill.

Intentionally or not, Udall has offered a resolution called "the Constitutional Option," the moniker the GOP gave its failed effort in 2005. Udall would abolish the requirement of a two-thirds majority for changing Senate rules, allowing a simple majority vote to abolish the filibuster.

McConnell, a soft-spoken leader whose parliamentary tactics have tied the chamber in knots, voices no worries that Democrats could be successful. "All majorities flirt with rules changes," he said. "My guess is most of the current majority aren't suffering from amnesia."

Filibusters of presidential appointees first gained prominence under Thomas A. Daschle (D-S.D.), the Senate minority leader who led the 2003 and 2004 logjam of more than 10 Bush White House nominees for the federal bench, an unprecedented volume of judicial filibusters.

Liberals who today yearn for Reid to force Republicans into the long-winded filibusters depicted in "Mr. Smith Goes to Washington" echo the similar pleading of conservative activists earlier this decade. But such rituals are outdated. Any unified bloc of 41 senators can impede progress without any requirement of actively debating the issue.

For media attention in 2007, Reid, as new majority leader, scheduled a round-the-clock debate on Iraq war funding, but it was a back-and-forth debate between the two sides and ended at a filibuster deadlock. Republicans, in 2003, did a similar stunt over Daschle-led filibusters, meeting the same fate.

The original filibuster rule, instituted in 1917 after just 11 senators blocked President Woodrow Wilson's effort to send arms to Europe in World War I, set the filibuster threshold at two-thirds of those present at a vote. The last successful effort to change the filibuster, led by then-Sen. Walter Mondale (D-Minn.) and other proponents of civil rights legislation, took more than 15 years to reach agreement in 1975 for a 60-vote requirement to stop debate.

Now many Democrats are hoping that if health-care reform dies in a messy filibuster, there will be a groundswell of support for rules changes. But this comes as independent handicappers predict Democrats could suffer net losses of four to seven seats in the November midterm elections. In 2012 and 2014, Democrats have to defend twice as many seats as Republicans, making it possible any abolition of the filibuster in the year ahead could hand over a majority-wins-all power to the GOP in a couple years.

Flummoxed by the constitutional and political predicament, Biden admitted: "I don't have the answer. You're about to ask me, but I don't have the answer. Look, all I'm saying is that I hope that cooler heads start to prevail."